Retatrutide for Health & Longevity - Quick Reference Sheet
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Retatrutide for Health & Longevity

Created on 08/08/2026 – Quick Reference based on Evidence Review created using AI4L / Opus 5 – Audit

An experimental weekly injection switching on three hormone systems simultaneously. It has produced the largest weight reduction of its kind, with striking falls in liver fat, better blood sugar, lower blood pressure, knee pain relief and better breathing in sleep. Costs are stomach upset, faster heart rate, odd skin sensations and muscle loss. No legal supply exists outside trials. (Full Review)

Protocol

Dose & route
2 mg weekly, subcutaneous
Once-weekly subcutaneous injection, started at 2 mg and continued indefinitely as an add-on to a reduced-calorie diet and increased physical activity.
Escalation
2 → 4 → 6 → 9 → 12 mg
Four-weekly steps; four weeks is the minimum sensible interval, since steady state is reached after four to five weekly doses.
Maintenance target
4, 9 or 12 mg
Maximum-dose targets 12 mg; tolerability-first stops at 4 mg, accepting roughly two-thirds of the weight loss for roughly one-third of the adverse-event discontinuation.
Time to effect
Weight loss
From week 4
Measurable by week 4, with appetite suppression noticeable in the first one to two weeks; the curves do not plateau, weight continuing to fall through 80 and 104 weeks.
Liver fat
24 weeks
Liver fat responds fastest, with over 80% relative reduction already at 24 weeks.
Blood sugar
12 weeks
Glycated haemoglobin reflects the change by week 12.

Benefits

Contraindications
  • Anyone outside a sanctioned clinical trial
  • Personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2
  • Prior pancreatitis or active pancreatic disease
  • Established gastroparesis
  • Type 1 diabetes
  • Pregnancy, attempts to conceive within the preceding two months, breastfeeding
  • Severe hepatic impairment (Child-Pugh Class C)
  • Dialysis-dependent kidney failure
  • Active symptomatic gallstone disease
  • Body mass index below 27 without a weight-related condition
  • History of an eating disorder involving restriction or purging
  • Diagnosed sarcopenia or grip strength below the age-and-sex reference threshold
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Key Interactions
  • Insulin and insulin secretagogues (insulin glargine, insulin aspart, glimepiride, glipizide, gliclazide)
  • Narrow-therapeutic-index oral drugs (warfarin, levothyroxine, digoxin, phenytoin, ciclosporin)
  • Oral contraceptives (ethinyl estradiol, drospirenone, levonorgestrel)
  • Other glucose-lowering and weight-lowering prescription agents (semaglutide, tirzepatide, liraglutide, metformin, empagliflozin, dapagliflozin)
  • Sedating and anticholinergic medications (opioids, anticholinergic bladder agents, tricyclic antidepressants)
  • Over-the-counter medications (ibuprofen, naproxen, aspirin, loperamide, bismuth subsalicylate, antacids, omeprazole, esomeprazole)
  • Supplements with additive glucose-lowering effects (berberine, chromium picolinate, bitter melon, cinnamon extract, alpha-lipoic acid, Gymnema sylvestre)
  • Supplements with additive gastrointestinal effects (high-dose magnesium citrate, psyllium, glucomannan, high-dose fish oil, iron salts)
  • Supplements that support the identified deficits (whey or casein protein, creatine monohydrate, vitamin D with vitamin K2, vitamin B12, calcium)
  • Alcohol
  • Procedural sedation and general anaesthesia
    •

Risk & Side Effects

  • High: Gastrointestinal adverse events; treatment discontinuation due to adverse events; cutaneous sensory disturbances; increased heart rate.
    •
  • Medium: Loss of lean mass; urinary tract infections; hypersensitivity and injection-related skin reactions; weight regain after discontinuation; micronutrient and protein inadequacy.
    •
  • Low: Acute pancreatitis (conflicted); gallbladder disease; low blood sugar in combination therapy; delayed gastric emptying and anaesthesia aspiration risk; hair shedding during rapid weight loss; contaminated or misidentified grey-market material.
    •
  • Speculative: Thyroid C-cell tumours; direct cardiac effects of glucagon receptor activation; effects on bone density; ophthalmic events; mood and psychiatric effects; adaptive reduction in metabolic rate after discontinuation.
    •

Monitoring

Marker Target Why
Body weight and waist circumference Waist under half of height Primary efficacy signal
Body composition (fat mass, lean mass, appendicular lean mass index) Appendicular lean mass index above 7.0 kg/m² in men, 5.5 kg/m² in women Detects lean-mass loss invisible on the scale
Grip strength Above 27 kg in men, 16 kg in women Functional confirmation that lost tissue was fat, not muscle
HbA1c 4.8–5.4% Average blood sugar over roughly three months
Fasting insulin and HOMA-IR Fasting insulin under 5 µIU/mL; HOMA-IR under 1.0 Insulin sensitivity, which improves earlier than average blood sugar
Fasting glucose 75–85 mg/dL Detects both hyperglycaemia and, with insulin co-therapy, hypoglycaemia
ALT and AST ALT under 20 U/L in men and 17 U/L in women; AST under 20 U/L in both Liver injury and liver-fat response
Liver fat fraction Under 5% The endpoint where retatrutide's distinctive mechanism acts
ApoB Under 80 mg/dL, or under 60 mg/dL at elevated cardiovascular risk Total burden of artery-clogging particles, more informative than low-density lipoprotein cholesterol
hsCRP Under 0.8 mg/L Low-grade systemic inflammation
Resting heart rate and blood pressure Resting heart rate 50–70 bpm; blood pressure under 120/80 mmHg The drug's most consistent adverse haemodynamic effect
eGFR and UACR eGFR above 90 mL/min/1.73 m²; UACR under 10 mg/g Kidney safety during dehydration risk, and kidney benefit signal
Lipase Within laboratory reference range Baseline for pancreatic safety
TSH 0.5–2.0 mIU/L Untreated thyroid dysfunction blunts metabolic response and confounds interpretation
Ferritin, vitamin B12, vitamin D (25-hydroxyvitamin D) Ferritin 50–150 ng/mL; vitamin B12 above 500 pg/mL; vitamin D 40–60 ng/mL Detects the micronutrient shortfall that follows a large drop in food intake
Serum albumin 4.0–5.0 g/dL Protein adequacy during sustained energy restriction

Cadence: Resting heart rate and weight weekly during escalation; a full laboratory panel at 12 weeks, then every 6 months while at a stable dose; body-composition scanning at baseline, 6 months and every 12 months thereafter.

Qualitative Assessment

  • Energy and training capacity: whether hard sessions still feel repeatable, or whether output is quietly declining alongside the scale weight.
  • Strength and physical function: ability to maintain load and repetitions in resistance training; stair-climbing and rising from a chair without hand support.
  • Appetite and eating pattern: whether hunger is suppressed to a workable degree or to the point that protein and micronutrient targets become unreachable.
  • Gastrointestinal tolerability: frequency and severity of nausea, vomiting, constipation and diarrhoea, tracked against dose steps.
  • Skin sensation: any tingling, burning or heightened sensitivity to touch, and whether it is settling with continued dosing.
  • Sleep quality and daytime alertness: including snoring and witnessed breathing pauses if sleep apnoea was present at baseline.
  • Mood and relationship with food: including any distress at the pace of body change, which was a documented reason for stopping in the trials.
  • Joint pain and mobility: particularly knee pain and walking distance where osteoarthritis was present.
Not medical advice. Educational distillation of a single evidence review. Confirm any decision with a qualified clinician, especially in the presence of prescription drugs or chronic conditions.